Re: using general IRQs

On Tue, 2015-08-11 at 06:45 +0300, Ran Shalit wrote:

On Tue, Aug 11, 2015 at 5:29 AM, Scott Wood [off-list ref] wrote:

quoted

On Mon, 2015-08-10 at 13:40 +0300, Ran Shalit wrote:

quoted

On Mon, Aug 10, 2015 at 10:48 AM, Ran Shalit [off-list ref] 
wrote:

quoted

Hello,

MPC8349 has general IRQ numbered 0-7,
It is required to bind these IRQs with some routine , i.e. they are
not used with any specific driver.

- Should they be configured as gpios in device tree so that we can use
the gpio as irq in linux ? Is there any example ?
- After configuration, can the gpios be used in linux using the
standard /sys/class/gpio ?

Regards,
Ran

What do you mean by "general IRQ"?  Do you mean external IRQs?

quoted

I am trying to use only IRQ4, so I have tried to configure it as
following in device tree:

device tree:

  intc@0{
 compatible = "intc";
 #address-cells = <1>;
 #size-cells = <0>;
 reg = <0 0x1000>;
 interrupts = <4 0x8>;
  };

But I don't see IRQ4 listed in the interrupt list:
# cat /proc/interrupts

/proc/interrupts shows virtual interrupts, which do not necessarily
correspond to anything in the device tree.  In particular, virtual 
interrupts
under 16 are reserved for ISA interrupts, and thus any mpic interrupts in
that range will be remapped.

Additionally, putting an interrupt in the device tree does not make it 
show
up in /proc/interrupts.  Only interrupts for which a driver has 
registered a
handler will show up in /proc/interrupts.

-Scott

Hi Scott,

I meant  external IRQ.
I am actually trying to use irq 4 interrupt.

I've added the above in device tree, and in kernel code I do:
np = of_find_node_by_name(NULL,"hello");

Why are you looking for a node named "hello" when your node is named "intc"?

  if (np == NULL)
    {
    printk("Error node not found\n");
    }
  printk("Node np = 0x%0x\n",np);                     <-- Node np = 
0xdfffe2f0

How could you possibly have gotten a non-NULL value for np, with the above 
code and node, unless there's something you're not showing?

  virq = irq_of_parse_and_map(np,0);

  printk(" VIRQ: %d \n" , virq);                              <-- virq = 0 
!!??

virq = 0 means the lookup failed.  Either there was no interrupt in the node, 
or it couldn't be mapped for some reason.

  if (0 > (error=request_irq(virq, &hello_IRQHandler, IRQF_SHARED,
"hello", &value))) {
      printk(KERN_WARNING"hello_IRQHandler: Init: Unable to allocate
IRQ error = %d\n\n", error);
    return -1;
  <-- request_irq return -22 ....
  }


 But it fails in request_irq (it return -22).
Also, irq_of_parse_and_map(np,0) returns 0. I think it should have returned 
4.

I already explained why it won't return 4 (see the part about virtual 
interrupts).

-Scott